When ‘parent’ uranium-238 decays, for example, it produces subatomic particles, energy and ‘daughter’ lead-206.
Isotopes are important to geologists because each radioactive element decays at a constant rate, which is unique to that element.
Geologists often need to know the age of material that they find.
They use absolute dating methods, sometimes called numerical dating, to give rocks an actual date, or date range, in number of years.
Each original isotope, called the parent, gradually decays to form a new isotope, called the daughter.
Each isotope is identified with what is called a ‘mass number’.
The changes can be chemical (compositional) and physical (textural) in character.Yet, it is the canyon’s rock walls that allow people to develop their greatest perspective on geologic time, because of these rocks’ immense age, their fossil record, and because these rocks formed in environments far different than those found in northern Arizona today.With a rock record that spans more than 1500 m.y., Grand Canyon is truly a panoramic view into the geologic past.Far from being data, these dates are actually interpretations of the data.As discussed before, the assumptions influence the interpretation of the data.